Abrasive assembly



May 24, 1938. I LQEWY I ABRAS IVE ASSEMBLY Filed March 20, 1937 Juuus E.L oEwY L35 BY M INVENTOR.

Patented May 24, 1938 UNITED STATES PATENT OFFICE Application March 20,

2 Claims.

My invention relates to an abrasive assembly especially adapted fororganically bonded abrasion wheels or those bonded with syntheticresins.

As is well known in the art, the problem of mounting abrasive wheels ofthe above type, especially cup wheels or similar wheels in which theface of the wheel is used for'cutting, rather than the peripheral edge,is a serious one. Some form of backing, plate for the wheel isconsidered 1 essential, not only for driving but also for strength andsafety. It has been common to form a union between the wheel and thebacking plate such that they are normally inseparable but this has madeit necessary to supply a backing plate with 1 5* each wheel, with theresult that when the wheel is'worn down, either the backing plate andthe remainder of the wheel is scrapped or the customer expects the plateto be salvaged and used again, a difiicult matter because of wear,inher- 20. cut formation, and frequently in the heavy industries,abnormal abuse. Moreover the baking of the wheel on its backing plate isattendant.

with some difliculties, including the handling and routing of theplates, and it must be remembered 25; that the high speeds of abrasivewheels and their very nature and function require that the safety factorin their use be predominantly considered in their structure andassembly. For high speed wheels a consideration of balance dictates amachined backing plate of high initial cost and the provision of such aplate with each wheel not only makes an original or a replacement unitexpensive but slows up production in the factory and tends in the fieldto cause the customer to 35 use his abrasive wheels to the very limitpoint with resulting danger to the operator.

An object of my invention is to provide an abrasive assembly ofsatisfactory structure comprising a separable wheel unit and a backingplate to which it may be removably secured or fastened to the end thatworn wheels may readilybe replaced by new ones using the same plate.

A further object is to provide such an abrasive assembly in which thefunction of the securing or fastening arrangement is solely to clamp theabrasive wheel to its backing and hold it on its driver and the driveris separately provided for, removing the strain of driving the Wheelfrom the securing members.

Still further objects are to provide a novel form of backing plate forthe purposes described and to provide as separable units the backingplate itself and a face grinding wheel without a backing plate suitablefor replacement or for origi- 1937, Serial No. 131,986

nal use on the backing plate and of relatively low cost.

With the foregoing and other objects in view, as will be apparent to.those skilled in the art as the description proceeds, my inventionresides in the combination and arrangement of parts and in the detailsand methods of construction described in this specification andparticularly pointed out in the appended claims, it being understoodthat changes may be made in the particular embodiment of the inventionwithin the scope of what is claimed, without departing from the spiritof the invention. I intend no limitation other than those of the claimswhen fairly interpreted in the light of the full disclosure-and thepresent state of the art.

In the drawing:

Fig. 1 is a back face view of an abrasive wheel according to myinvention;

Fig. 2 is a sectional elevation on the line 22 of Fig. 1;

Fig. 3 is a wheel face View of a backing plate according to myinvention;

Fig. 4 is a sectional elevationon the line 4-4- of Fig. 3;

Fig. 5 is a grinding face view of an abrasive assembly according to myinvention;

Fig. 6 is a sectional elevation of the grinding assembly of Fig. 5.

Similar reference characters refer to corresponding parts in the severalviews.

In the type of abrasive assembly to which this invention has particular,but not exclusive, application, the grinding wheel is formed by a mix ofabrasive materials and a binder poured into a mold as a dry powder, thewhole pressed to form, taken out of the mold, baked, and faced with acutter. Such a wheel I is preferably disk shaped with a central opening3, usually circular in section. Coaxial therewith, in this embodiment ofmy invention illustrated in the drawing, is a driving socket 4,preferably square with bevelled corners, recessed into the back face ofwheel I. I prefer to centralize this driving socket because at thislocation it takes the least strength out of the wheel.

It is difficult to hold such a recessed socket to size in various wheelswith various abrasives and even if of the proper size originally, itwould be affected by use and would itself tend to abrade any lug orprojection contacting it. I prefer, therefore, to metallically line thesocket as with lead 5, making the recess a good fit to the drivingprotuberance 9 which may be integral with, welded to, or otherwisefastened to the driving or backing plate 6 (Fig. 3).

At equally spaced points and embedded into the wheel 5 are a pluralityof nut-like members 2, 2, internally threaded for the reception ofsecuring members 12, l 2, (Fig. 6) which pass through openings l, i, inthe backing plate 5, and clamp the wheel 5 and the plate 5 together. Thereceivers 2, 2, are of limited depth, not greater than the drivingsocket 3, and are accessible from the back or plate face of the wheel I.In this instance, hexagon or square nuts are turned down at the exposedend so that the receiver is larger at the inner end in order to be moresecurely held. A multiface nut is preferred, in place of a round nut, tolessen the possibility of its turning.

A suitable backing plate 6 is provided of cup shape, that is, with anupstanding edge portion or rim 8. To fit the driving socket i of thegrinding wheel i, there is provided a driving protuberance projectingfrom the wheel surface of the backing plate, not beyond the projectionof the rim 8, but preferably flush with this rim which permits thelatter to serve as .a visual indicator and guard as the wheel wearsdown. The operator is by this means enabled to know that he is not indanger of wearing the Wheel to any embedded part.

To secure the backing plate 6 to any driving shaft on which it is to bemounted, a central threaded opening iii is provided in the plate and tofacilitate threading the plate 6 on such shaft (not shown) spanner holesH, H, may be provided. The construction described of the cupshapedbacking plate 6 with an upstanding edge 8 and, in this case, a centrallypositioned driving protuberance 9, provides an annular space or recess l3 surrounding the projection 9 and within the rim 8, to receive thewheel i. The wheel I seats in this recess i3 and is held clamped to theplate 6 by the fastening members l2 when suitably driven into placethrough the aligned openings l, I, which are preferably counterbored(Fig. 6). With such structure, the screws 52 have the sole duty offastening plate 6 and wheel I together, holding the driving protuberance9 into the fitted driving socket i, and thus permitting all the drivingstrain to be transmitted through this positive driving connection ratherthan through the fastening screws.

By making the driving protuberance 9 square, and properly spacing theopenings I, l, in the backing plate, preferably at 90 degrees apart, andcorrespondingly spacing the internally threaded receivers 2, 2, thelatter will be automatically aligned with openings 1, 'i, in whateverposition the wheel l is placed on the backing plate 6, as the fitting ofthe protuberance 9 into the socket 4 thus positions the wheel to beclamped.

What I claim is:

1. An abrasive assembly comprising an abrasive wheel, a backing plateseparable therefrom provided with spaced openings, threaded membersadapted to secure said wheel and plate together, internally threadedreceivers for said threaded securing members embedded in said wheel andspaced for alignment with said plate openings when said wheel ispositioned on said backing plate, a driving protuberance on the Wheelface of said backing plate and connected thereto and a metallicallylined receiving socket in the back face of said wheel fitted to saidplate protuberance whereby to position said wheel on said plate foralignment of said internally threaded receivers and said plate openingsand to drive said wheel when said plate is driven.

2. An abrasive assembly comprising a backing plate provided with anupstanding edge portion and a central driving protuberance projectingfrom said plate and substantially flush with said edge portion wherebyto provide an annular recess in said plate surrounding said protuberanceand within said edge portion, an abrasive wheel centrally provided witha. receiving socket fitted to said driving protuberance, said wheel soconstructed and of such dimensions as to seat in said annular recess,and securing members adapted and arranged to removably fasten said plateand Wheel together.

JULIUS E. LOEWY.

